Performance Of Medical Devices Research Articles

Reducing the Memory Requirements of High Resolution Voxel Phantoms by Means of a Binary Tree Data Structure

Computational human phantoms are a well-established tool used to simulate the performance of medical imaging devices. The maximum resolution of voxelized phantoms is bounded in practice by the available computer memory, which is especially limited for graphics processing unit (GPU)-based simulations. For phantoms that have been segmented into a small number of tissue types, the use of a uniform grid is inefficient because large numbers of adjacent voxels are composed of the same tissue. The computer files used to store these phantoms can be compressed into a small fraction of their original size using standard lossless compression algorithms. Compression is used for storage and distribution, but not during the simulations because compression algorithms compress the data incrementally from the first byte to the last. This approach intrinsically prevents access to random locations along the data stream, which is an essential requirement of the majority of simulation algorithms. In this paper, we propose to store voxelized phantoms in memory using a binary tree structure, as a way to accomplish both data compression and fast random access. The composition of a particular voxel can be efficiently retrieved by traversing the binary tree down from the root node to the corresponding leaf node. As a drawback, the memory savings come at the cost of more frequent memory access, which might slow down simulations in which memory access constitutes a substantial fraction of the execution time. Methods to generate and efficiently store in memory a binary tree geometry, and an example implementation in a GPU-accelerated Monte Carlo code for X-ray imaging virtual clinical trials, are presented. Results of a simulation of mammography and tomosynthesis imaging with a computational breast phantom voxelized at 50 μm show that the implemented binary tree geometry can achieve a 50-fold reduction of memory use, with a 4.7% increase in simulation time.

Improving medical device safety and performance: From passive reporting to active surveillance and beyond

Medical device use is expanding with the emergence of sophisticated applications to gather, store, process and communicate patient-centric data. Diversity, fast-paced technological advances and complex interfaces between users and technology complicate challenges associated with promoting medical device safety. The purpose of this conceptual paper is to evaluate strategies for improving medical device safety and performance through collaborative evidence generation and innovative analytics. Developing public–private partnerships and the infrastructure for active surveillance, evidence generation and data analytics requires engaged and enlightened institutional leadership who share a common vision and values. Integration of interprofessional initiatives may remediate the silo mentality pandemic in the healthcare community, harness the digital revolution for surveillance and promote improvements in medical device safety and performance.

Coatings Boost Medical Device Performance

By applying PVD coatings to surgical instruments, implants and other medical devices, OEMs can increase value and differentiate products with functional properties.

Inter-Laboratory Characterization of the Velocity Field in the FDA Blood Pump Model Using Particle Image Velocimetry (PIV).

A credible computational fluid dynamics (CFD) model can play a meaningful role in evaluating the safety and performance of medical devices. A key step towards establishing model credibility is to first validate CFD models with benchmark experimental datasets to minimize model-form errors before applying the credibility assessment process to more complex medical devices. However, validation studies to establish benchmark datasets can be cost prohibitive and difficult to perform. The goal of this initiative sponsored by the U.S. Food and Drug Administration is to generate validation data for a simplified centrifugal pump that mimics blood flow characteristics commonly observed in ventricular assist devices. The centrifugal blood pump model was made from clear acrylic and included an impeller, with four equally spaced, straight blades, supported by mechanical bearings. Particle Image Velocimetry (PIV) measurements were performed at several locations throughout the pump by three independent laboratories. A standard protocol was developed for the experiments to ensure that the flow conditions were comparable and to minimize systematic errors during PIV image acquisition and processing. Velocity fields were extracted at the pump entrance, blade passage area, back gap region, and at the outlet diffuser regions. A Newtonian blood analog fluid composed of sodium iodide, glycerin, and water was used as the working fluid. Velocity measurements were made for six different pump flow conditions, with the blood-equivalent flow rate ranging between 2.5 and 7 L/min for pump speeds of 2500 and 3500rpm. Mean intra- and inter-laboratory variabilities in velocity were ~ 10% at the majority of the measurement locations inside the pump. However, the inter-laboratory variability increased to more than ~ 30% in the exit diffuser region. The variability between the three laboratories for the peak velocity magnitude in the diffuser region ranged from 5 to 25%. The bulk velocity field near the impeller changed proportionally with the rotational speed but was relatively unaffected by the pump flow rate. In contrast, flow in the exit diffuser region was sensitive to both the flow rate and the rotational speed. Specifically, at 3500rpm, the exit jet tilted toward the inner wall of the diffuser at a flow rate of 2.5 L/min, but the jet tilted towards the outer wall when the flow rate was 7 L/min. Inter-laboratory experimental mean velocity data (and the corresponding variance) were obtained for the FDA pump model and are available for download at https://nciphub.org/wiki/FDA_CFD . Experimental datasets from the inter-laboratory characterization of benchmark flow models, including the blood pump model presented herein and our previous nozzle model, can be used for validating future CFD studies and to collaboratively develop guidelines on best practices for verification, validation, uncertainty quantification, and credibility assessment of CFD simulations in the evaluation of medical devices (e.g. ASME V&V 40 standards working group).

Advancing Regulatory Science With Computational Modeling for Medical Devices at the FDA's Office of Science and Engineering Laboratories.

Protecting and promoting public health is the mission of the U.S. Food and Drug Administration (FDA). FDA's Center for Devices and Radiological Health (CDRH), which regulates medical devices marketed in the U.S., envisions itself as the world's leader in medical device innovation and regulatory science–the development of new methods, standards, and approaches to assess the safety, efficacy, quality, and performance of medical devices. Traditionally, bench testing, animal studies, and clinical trials have been the main sources of evidence for getting medical devices on the market in the U.S. In recent years, however, computational modeling has become an increasingly powerful tool for evaluating medical devices, complementing bench, animal and clinical methods. Moreover, computational modeling methods are increasingly being used within software platforms, serving as clinical decision support tools, and are being embedded in medical devices. Because of its reach and huge potential, computational modeling has been identified as a priority by CDRH, and indeed by FDA's leadership. Therefore, the Office of Science and Engineering Laboratories (OSEL)—the research arm of CDRH—has committed significant resources to transforming computational modeling from a valuable scientific tool to a valuable regulatory tool, and developing mechanisms to rely more on digital evidence in place of other evidence. This article introduces the role of computational modeling for medical devices, describes OSEL's ongoing research, and overviews how evidence from computational modeling (i.e., digital evidence) has been used in regulatory submissions by industry to CDRH in recent years. It concludes by discussing the potential future role for computational modeling and digital evidence in medical devices.

Synergy on Surfaces: Anti-Biofouling Interfaces Using Surface-Attached Antimicrobial Peptides PGLa and Magainin-2.

The synergistic effect of antimicrobial compounds is an important phenomenon that can increase the potency of treatment and might be useful against the formation of biofilms on surfaces. A strong inhibition of microbial viability on surfaces can potentially delay the development of biofilms on treated surfaces, thereby enhancing the performance of water-purification technologies and medical devices, for example, to prevent hospital-acquired infections. However, the synergistic effects of surface-immobilized antimicrobial peptides (AMPs) have not yet been reported. Here, we demonstrate the synergistic antimicrobial effects of the AMPs PGLa and magainin-2 on modified reverse-osmosis (RO) membranes. These AMPs are known to act synergistically in the free state, but their antimicrobial synergistic effects have not yet been reported in a surface-immobilized state. The AMPs were functionalized with alkyne linkers and covalently attached to RO membranes modified with azides, using a click chemistry reaction. The resulting RO membranes showed reduced contact angles, indicating increased wettability. X-ray photoelectron spectroscopy confirmed the presence of the two peptides on the membranes via changes in the amounts of carbon, oxygen, and sulfur, which led to an increased S/C ratio, probably because of the sulfur present in the methionine residue of the peptides. The synergistic activity was measured with the free peptides in solution and covalently bound on RO membrane surfaces by observing increased leakage of 5(6)-carboxyfluorescein from large unilamellar vesicles. The synergistic antimicrobial activity against Pseudomonas aeruginosa was observed using surface-activity assays, where the AMP-modified RO membranes showed an effective inhibition of P. aeruginosa biofilm growth, as compared with unmodified membranes. An enhanced activity of antimicrobials on surfaces might lead to potent antimicrobial surfaces, which could result in more fouling-resistant water-treatment membranes.

Safety of orogastric tubes in foregut and bariatric surgery

BackgroundOrogastric tubes have traditionally aided foregut procedures with sizing and organ protection. The rise of bariatric surgery has led to the creation of novel medical devices aimed at facilitating the laparoscopic sleeve gastrectomy. While approved by the FDA, the long-term safety profile of these devices in the general population is often unknown. This review looks at complications associated with novel Orogastric Tubes compared to the traditional bougie.MethodsWe performed a review of the Food and Drug Administration’s (FDA) Manufacturer and User Facility Device Experience (MAUDE) database for complications associated with the traditional bougie, Boehringer Labs ViSiGi 3D® and the Medtronic GastriSail™ since 2011. In addition, we looked for reported cases in the literature of complications with these devices.ResultsOverall complication rates reported in the MAUDE database varied in number and severity. The bougie had seven reported complications, one of which was an organ perforation. The ViSiGi 3D® had zero reported complications. The GastriSail™ had 36 total reported complications with 17 perforations. A literature review shows that rates of bougie complications are extremely rare with no case reports or reviews of complications from the novel orogastric tubes.ConclusionsThe complication rates between the traditional bougie and novel devices vary in number and severity, with the GastriSail™ having the highest reported complication rate. Despite rigorous testing for FDA approval, ongoing research into performance of new medical devices in the general population remains important.

Effects of Transient Exposure to High Shear on Neutrophil Rolling Behavior.

Neutrophils display an array of behaviors ranging from rolling and migration to phagocytosis and granule secretion. Several of these behaviors are modulated by the local shear conditions. In the normal circulation, neutrophils experience shear rates from approximately 10-2,000 s-1. However, neutrophils are also exposed to pathological shear levels in natural conditions such as severe stenosis and arteriosclerosis, as well as in blood-contacting devices such as ventricular assist devices (VADs) and hemodialysis machines. The effects of transiently (< 1 sec) exposing neutrophils to abnormally high shear rates (>3,000 s-1) are not well understood. We developed a set of microfluidic devices capable of exposing neutrophils to high shear rates for short durations (100-400 msec). Suspensions of isolated neutrophils were perfused through the devices and their rolling velocities on P-selectin were analyzed before and after shear exposure. We observed a significant increase in neutrophil rolling velocities on P-selectin coated regions following transient high shear exposure. The magnitude of the rolling velocity increase was dependent upon the duration of high shear exposure and became statistically significant for exposure times of 310 msec or longer. When polystyrene beads coated with a glycosulfopeptide that mimics the binding region of P-selectin glycoprotein ligand-1 (PSGL-1) were perfused through the devices, no change between the pre-shear and post-shear rolling velocities was observed. These results suggest that high shear levels alter normal neutrophil rolling behavior and are important for understanding neutrophil biology in high shear conditions, as well as for improving medical device performance.

Safety evaluation and consideration of 4Pin Multi-needle for meso-therapy.

This study was conducted according to the method presented in the Republic of Korea Pharmacopoeia 11th Revision, aseptic test method to evaluate the suitability of sterilization for a sterile needle (4 Pin Multi-needle). In this study, four tests were conducted: sterility test, cytotoxicity test, acute toxicity test, skin sensitization test. First, in the aseptic test, the microorganism was not proliferated in the aseptic test of the medium. As a result of the performance test of the medium, it was confirmed that the microorganism developed within 3 days and the fungus was evident within 5 days. Based on this, it was confirmed that the medium was suitable, and as a result of the aseptic test, the development of microorganisms was not observed during the total culture period. Based on these results, tests were conducted which were confirmed to be suitable for aseptic testing because the development of bacteria on the provided samples was not recognized. For cytotoxicity tests ISO10993-5; 2009 (Biological Evaluation of Medical Devices, Part 5: Test for in vitro Cytotoxicity). As a result, the MEM eluate of the test substance caused very slight cytotoxicity to the fibroblasts of the mouse and was judged to be Grade 1 (Slightly cytotoxic) according to the judgment standard of ISO 10993-5. On the other hand, solvent control, negative control and positive control showed the expected results on the test. Acute Toxicity Test Results: It was judged that there was no systemic toxicity change when ICR mice were treated with 50 mL/kg B.W. of the eluate of sterile injectable needle for 72 hours. Skin sensitization test result: The Hartley guinea pig was evaluated as a substance which is evaluated as a substance which does not induce any skin reaction when skin sensitization is applied to the dissected material of the sterile injectable needle and is weak in skin sensitivity. Based on the above tests, we will study the stability and efficacy of more reliable medical devices based on the verification and performance of medical devices.

Effect of working gas composition in medical needle sharpening by ion beam sputtering

The sharpness of cutting edges and apexes is crucial in the performance of various medical devices. A method of medical needle finishing, consisting of large area ion beam sputtering, is introduced and studied. Significant deburring, edge sharpening and surface modification of the needles is demonstrated by an experiment. The influences of working gas composition and total ion fluence on the resulting needle properties are emphasized. It was shown that the utilization of an Ar/dry air mixture (37/6) resulted in a significant improvement in surface morphology, compared to pure Ar sputtering. The effect of gas composition is discussed in terms of concurrent material sputtering and chemisorption of reactive species. Needle sharpening aspects studied using microscopy techniques were confirmed by measuring the force required to push a needle through a plastic film. The puncture force of an as-grinded needle was reduced by ∼50% by means of the reported method.

Issues in evaluating the user performance of new home medical devices: a field test of two devices produced by a leading provider

Purpose: this paper reports a case study, which investigates the approach to testing user performance of home medical devices (HMDs) produced by a leading provider in the sector. Method: we field-tested two HMDs with 41 users, and deployed both the provider's approach and our own to compare the results. Results: the results revealed three issues concerning the provider's approach: usability features had little to do with the positive user feedback; lack of understanding of the characteristics of the target audience; and conflicting results related to user performance and preference. The causes were related to the purpose of the user testing, to the expertise of the staff undertaking it, and to the tacit and unarticulated nature of users' experience and expectations. Conclusions: the user performance of some existing HMDs may not reflect critical user needs and expectations since the positive user feedback might be produced by flawed testing approaches adopted by the provider.

Issues in evaluating the user performance of new home medical devices: a field test of two devices produced by a leading provider

Issues in evaluating the user performance of new home medical devices: a field test of two devices produced by a leading provider

VP24 HTA To Assess Esthetic Procedures In France: Haute Autorité de Santé (HAS) Seven Year Experience

Introduction:The Health Technology Assessment (HTA) of esthetic procedures was performed by the French National Authority for Health (HAS), at the request of the French Ministry of Health (MoH), and under a new regulatory framework enabling the government to ban esthetic procedures considered harmful or potentially harmful to patients and consumers by HAS. Objectives: Describe HAS’ seven year experience with the safety assessment of four esthetic procedures.Methods:This is an HAS review of its methods used in four HTAs for the following evaluated techniques: lipolysis; cryolipolysis; esthetic mesotherapy; and, ultraviolet (UV) radiation in tanning devices. The review aimed to describe how these assessments have been undertaken and information sources used, from 2010 to 2017, to appreciate the safety profile of these procedures.Results:A systematic literature review (SRL) and analysis was performed for all four HTAs. Since findings did not allow for thorough appreciation of safety, additional sources of information were consulted to address evidence gaps. Sources may have included any combination of the following: i) National and international health care authority data and alerts ii) Legal and ethical frameworks iii) Public consultation iv) Expert opinion v) Patient-consumer association opinion vi) Economic analysisConclusions:An adaptation of the HTA methodology was necessary to meet the specific requirements of these assessments. Despite sources accumulated and consulted within the seven year period, quantitative data were found insufficient to fully appreciate the safety profile for any one of the studied esthetic procedures. National regulatory reinforcement on the reporting of adverse events, with implementation of a centralized online tool, is expected to generate and capture reliable data on the frequency and severity of adverse events associated with esthetic procedures. Recent European Union (EU) regulatory requirements on the safety and performance of medical devices include equipment used for esthetic procedures, indicating agreement and alignment on national and EU-level monitoring efforts.

A comparative study of polyethylene terephthalate surface carboxylation techniques: Characterization, in vitro haemocompatibility and endothelialization

Surface functionalization of polymers is crucial for improving biocompatibility and haemocompatibility, which correlates to improved performance of medical devices. Here, we have evaluated the effect of four PET surface carboxylation techniques on the antifouling property, haemocompatibility, and endothelialization. Surface carboxylation was achieved by formaldehyde+bromoacetic acid treatment (PET-1[COOH]), methacrylic acid grafting (PET-2[COOH]), NaOH hydrolysis+KMnO4 oxidation (PET-3[COOH]), and oxygen plasma treatment+acrylic acid grafting (PET-4[COOH]). The carboxyl densities on these surfaces were 0.4, 23.2, 31.9, 16.4nmol/cm2, respectively. XPS and FTIR spectroscopy confirmed the introduction of carboxyl groups. Water contact angle results showed that hydrophilicity increased with an increase in surface carboxyl density. SEM images confirmed that these modifications didn't cause any surface deterioration. AFM studies showed an increase in surface roughness of the carboxylated PET. Tensile testing showed that these modifications did not affect the bulk properties. Compared to control, PET-3[COOH] has a 9-fold reduction in BSA adsorption. Haemocompatibility studies showed significantly reduced %hemolysis and platelet adhesion on the carboxylated PET. Cell culture studies revealed that endothelial cell (EA.hy926) attachment increased with increase in surface carboxyl density. PET-3[COOH] showed the most improved haemocompatibility and endothelial cell attachment. These results clearly show that the method of functionalization has a significant impact on the haemocompatibility and cell attachment.

CONDUCIVE ENVIROMENT FOR FOSTERING INDIA SPECIFIC INNOVATION: NEW MEDICAL DEVICE RULES 2017

The medical technology sector in India valued at approximately $ 10 billion in 2015 at end consumer prices and is growing at 10-12 percent annually. Currently, the Indian medical devices industry represents just over 2 percent of the global medical device market. With such immense potential, some of the challenges that this industry faced with lack of framework. India’s medical device sector was greeted by a breakthrough announcement during union budget speech in 2017. India’s finance minister declared that the government would formulate new norms, ‘harmonized with international rules’, for the medical devices sector. Post which Ministry of Health and Family Welfare released a media statement that it had notified the Medical Device Rules 2017 on Jan 31st, which would be enforceable from January 2018. These new medical device rules would attract more foreign investment and reduce prices of medical devices. This positive policy push for the development of the domestic medical device market will potentially bring more devices under its ambit, the new medical rules will bring in a huge wave of relief to consumers, protecting their right to access high quality and safe products. As the fastest growing healthcare market in the world, the government can further take several measures to create a conducive environment to consolidate the growth of the medical devices sector with regularly advising new guidances. The recent notification on essential principles for safety and performance of medical device, risk based classification with list of medical devices and in-vitro diagnostics, notified bodies auditing the firms demonstrates the favorable environment for manufacturing of medical devices nurturing growth and innovation in the country.

Increased X-ray Visualization of Shape Memory Polymer Foams by Chemical Incorporation of Iodine Motifs.

Shape memory polymers can be programmed into a secondary geometry and recovered to their primary geometry with the application of a controlled stimulus. Porous shape memory polymer foam scaffolds that respond to body temperature show particular promise for embolic medical applications. A limitation for the minimally invasive delivery of these materials is an inherent lack of X-ray contrast. In this work, a triiodobenzene containing a monomer was incorporated into a shape memory polymer foam material system to chemically impart X-ray visibility and increase material toughness. Composition and process changes enabled further control over material density and thermomechanical properties. The proposed material system demonstrates a wide range of tailorable functional properties for the design of embolic medical devices, including X-ray visibility, expansion rate, and porosity. Enhanced visualization of these materials can improve the acute performance of medical devices used to treat vascular malformations, and the material porosity provides a healing scaffold for durable occlusion.

Post market surveillance in the german medical device sector – current state and future perspectives

Medical devices play a central role in the diagnosis and treatment of diseases but also bring the potential for adverse events, hazards or malfunction with serious consequences for patients and users. Medical device manufacturers are therefore required by law to monitor the performance of medical devices that have been approved by the competent authorities (post market surveillance). Conducting a nationwide online-survey in the German medical device sector in Q2/2014 in order to explore the current status of the use of post market instruments we obtained a total of 118 complete data sets, for a return rate of 36%. The survey included manufacturers of different sizes, producing medical devices of all risk classes. The post market instruments most frequently reported covered the fields of production monitoring and quality management as well as literature observation, regulatory vigilance systems, customer knowledge management and market observation while Post Market Clinical Follow-up and health services research were being used less for product monitoring. We found significant differences between the different risk classes of medical devices produced and the intensity of use of post market instruments. Differences between company size and the intensity of instruments used were hardly detected. Results may well contribute to the development of device monitoring which is a crucial element of the policy and regulatory system to identify device-related safety issues.

Collagen affinity coating for surface binding of decorin and other biomolecules: Surface characterization.

The development of biomaterials that promote tissue reconstruction and regeneration can reduce the low level, chronic inflammation and encapsulation that impact the performance of today's medical devices. Specifically, in the case of implantable sensors, the host response often leads to poor device performance that discourages permanent implantation. Our goal is to present on medical implants bioactive molecules that can promote healing rather than scarring. Localized delivery of these molecules would also minimize the possibility of adverse tissue reactions elsewhere in the body. Toward this end, the authors have developed a collagen affinity coating that binds a number of potential healing molecules and can be attached to the surface of an implanted biomaterial. This allows the creation of a wide variety of natural surface coatings that can be evaluated and tailored to promote the desired healing response. To demonstrate the efficacy of this collagen affinity coating to biospecifically bind promising healing molecules to type I collagen in vivo, the antifibrotic proteoglycan decorin was utilized. Decorin binds and renders ineffective the protein transforming growth factor beta (TGFβ) that induces collagen scar production. Thus, an assembled, supramolecular structure of biomaterial-collagen-decorin-TGFβ is formed. A decorin surface coating was created and characterized, illustrating the potential of this type I collagen affinity coating for widespread use with a variety of promising healing molecules. Future studies will test the implant efficacy of this type of coating.

Constructing the informatics and information technology foundations of a medical device evaluation system: a report from the FDA unique device identifier demonstration.

The US Food and Drug Administration (FDA) has recognized the need to improve the tracking of medical device safety and performance, with implementation of Unique Device Identifiers (UDIs) in electronic health information as a key strategy. The FDA funded a demonstration by Mercy Health wherein prototype UDIs were incorporated into its electronic information systems. This report describes the demonstration's informatics architecture. Prototype UDIs for coronary stents were created and implemented across a series of information systems, resulting in UDI-associated data flow from manufacture through point of use to long-term follow-up, with barcode scanning linking clinical data with UDI-associated device attributes. A reference database containing device attributes and the UDI Research and Surveillance Database (UDIR) containing the linked clinical and device information were created, enabling longitudinal assessment of device performance. The demonstration included many stakeholders: multiple Mercy departments, manufacturers, health system partners, the FDA, professional societies, the National Cardiovascular Data Registry, and information system vendors. The resulting system of systems is described in detail, including entities, functions, linkage between the UDIR and proprietary systems using UDIs as the index key, data flow, roles and responsibilities of actors, and the UDIR data model. The demonstration provided proof of concept that UDIs can be incorporated into provider and enterprise electronic information systems and used as the index key to combine device and clinical data in a database useful for device evaluation. Keys to success and challenges to achieving this goal were identified. Fundamental informatics principles were central to accomplishing the system of systems model.

Effective Use of Foreign Clinical Data in Approvals for Medical Devices in Japan

Initial clinical development of medical devices occurs mainly in the USA and EU, with many medical devices registered in Japan afterwards. As the clinical performance of medical devices is less sensitive to ethnicity than the efficacy and safety of a drug, the performance of such devices can often be evaluated using foreign clinical data. The factors affecting the requirement for Japanese clinical data was investigated in the Japanese approvals of 103 high-risk devices, occurring between April 2005 and March 2015. The requirement for Japanese clinical data was associated with no approval in the USA and EU and the absence of foreign clinical data in the submission (p&lt;0.001). Our results suggest that Japanese clinical data are not an essential requirement when foreign clinical data are included in the Japanese data package for approval, although, for 50% of devices with approval in the USA or EU, Japanese clinical data were still required for the Japanese approval. Reasons for this included the possibility that the performance of the device was sensitive to ethnicity associated with the medical environment, and that the device had been updated from the original one.https://doi.org/10.21423/jrs-v05n01p035 (DOI assigned 4/17/2019)